Carburetor idle control means

ABSTRACT

A carburetor idle control screw, comprising an elongate screw having an inner end received in the idle fuel discharge port of a carburetor and having an outer end extending outwardly of the carburetor into the atmosphere, said screw having an axial passageway therethrough opening thus the inner and outer ends thereof and a radial passageway therein between the ends thereof in communication with the axial passageway and adapted to be placed in registry with the idle fuel supply passage of the carburetor, said inner end of the screw projecting beyond the wall of the throat of the carburetor and into the throat, so that air is drawn into the axial passageway and mixed with fuel from the idle fuel supply passageway and the mixed air and fuel are introduced into the throat of the carburetor spaced from the wall thereof and the fuel is then atomized and thoroughly mixed with air, resulting in less fuel consumption and reduced air pollution.

United States Patent Martin July 22, 1975 CARBURETOR IDLE CONTROL MEANS{76] Inventor: Frank T. Martin, 925 Majorca Ave., Prlmary Examiner-TmMlles Coral Gables Fla 3334 Attorney, Agent, or F1rmShoemaker andMattare pp 4771317 A carburetor idle control screw, comprising anelongate screw having an inner end received in the idle [52] CI H 261/41zen/DIG. 251/310 fuel discharge port of a carburetor and having an [5 1]Int. Cl. FllZm 3/08 Outer end extending outwardly of the Carburetor into58 Field of sealchQwmf. 1. 261/411) D10 38- amwsphere said screw havingpassageway 251/3; therethrough opening thus the inner and outer endsthereof and a radial passageway therein between the [56] Reerences Citedends thereof in communication with the axial passageway and adapted tobe placed in registry with the idle UNITED STATES PATENTS fuel supplypassage of the carburetor, said inner end 2,7l L883 6/1955 Reeves26l/DIG. 38 of h screw projecting beyond the wall of the throat ct ofthe carburetor and into the throat, so that air is 3346244 OM96. LES261mm 38 drawn into the axial passageway and mixed with fuel 3'348823W967 Zed/DIG: 38 from the idle fuel supply passageway and the mixed air3:374:99l 3/1963 w lk I I M 261/41 D and fuel are introduced into thethroat of the carbure- 3,437,320 4/1969 Walker et at." 261/41 1) torSpaced from the wall thereof and the fuel is then 3,834,675 9/1964Farrow 26l/DlG1 38 atomized and thoroughly mixed with air, resulting inFOREIGN PATENTS OR APPLICATIONS less fuel consumption and reduced airpollution.

329,749 11/1920 Germany 261/41 D 7 Claims, 6 Drawing Figures CARBURETORIDLE CONTROL MEANS BACKGROUND OF THE INVENTION The present'inventionrelates to idle control means for carburetors for internal combustionengines, and more particularly. to an idle control screw for controllingthe idle of carburetors for most efficient operation of an engine withwhichthe carburetor is associated under conditions of engine idling andautomotive vehicle coasting and deceleration and the like.

When an internal combustion engine is idling or when automotiveequipment is decelerating or coasting, the throttle valve of thecarburetor is in closed position and fuel is supplied to the enginethrough the carburetor idle system in bypassing relationship to thethrottle valve or throttle plate. The fuel-air mixture supplied to theengine during these conditions is generally too rich and is also wetbecause of the failure of the air to atomize the fuel properly.Consequently, the fuel is not combusted efficiently by the engine anduneconomical operation of the engine under idling, coasting anddecelerating conditions results, with increased fuel consumption and airpollution.

In accordance with the present invention, a unique idle mixture controlscrew is provided, which introduces air into the fuel before the fuel issupplied to the throttle bore of the carburetor, and the air and fuelare thus premixed, and moreover, the idle screw of the present inventionextends substantially into the throttle bore so that the air-fuelmixture is introduced into the throttle bore in spaced relation to theside wall of the carburetor, with the result that the fuel is thoroughlyatomized and the air and fuel are effectively intermixed with the resultthat the engine operates more efficiently and both fuel consumption andair pollution are reduced.

Still further, with the present invention the air-fuel ratio ismaintained at a proper relationship even during conditions of idle andthe components of the engine accordingly have a longer life.

The results obtained with the present invention, as described brieflyabove, are not possible with prior art idle mixture screws, the majorityof which comprise screws having solid, elongate, conically shaped nosesor needle tips which are arranged to seat in the idle discharge port inthe carburetor and are adjustable relative thereto to control the amountof fuel passing through the discharge port around the needle on the idlemixture adjusting screw.

Other prior art devices, as exemplified, for example, by US. Pat. No.2,816,573, have air passage means extending through the idle adjustingscrews, but these devices still include a conically shaped nose orneedle 24 which is arranged to be adjusted relative to a seat 22 tocontrol the flow of fuel from an idle supply passage 18 through the idledischarge port 16 into the throat of the carburetor. Accordingly, thefuel tends to flow downwardly along the wall of the carburetor throatand to adhere thereto and thorough atomization of the fuel and completeintermixing between the air and fuel is not attained.

OBJECT OF THE INVENTION An object of the invention is to provide acarburetor idle control screw having passage means therethrough foradmitting atmospheric air and including further passage means for theintroduction of fuel to the interior of the screw for mixing of the airand fuel, said screw projecting at its inner end into the throat of acarburetor, so that the air-fuel mixture is introduced into thecarburetor spaced from the wall thereof for complete atomization of thefuel and thorough intermixing of the air and fuel prior to combustionthereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional viewthrough a typical carburetor having the idle adjusting screw of theinvention positioned therein.

FIG. 2 is a fragmentary view in section taken along line 2-2 of FIG. 1.

FIG. 3 is a greatly enlarged, fragmentary sectional view of a portion ofthe carburetor of FIG. 1 with the idle adjusting screw of the inventionoperatively positioned therein.

FIG. 4 is a still further enlarged, fragmentary sectional view takenalong line 4-4 of FIG. 3.

FIG. 5 is a view similar to FIG. 4, with the idle adjusting screw in adifferent operative position, for restricting the flow of fueltherethrough.

FIG. 6 is an enlarged, perspective view of the idle ad justing screw ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION In the drawings, wherein likereference numerals indicate like parts throughout the several views, acarburetor is indicated generally at C and includes an upper portion 10defining an air horn l1 and a lower portion or body 12 having a throttlebore or carburetor throat I3 therethrough. A venturi 14 is formed in thecarburetor between the air horn I1 and throat or throttle bore 13, and abridge or cross member 15 extends across the interior of the carburetorabove the venturi I4 and a main discharge nozzle I6 projects downwardlyto the venturi 14. The discharge nozzle 16 is in communication with afloat chamber 17 for supply of fuel to the discharge nozzle and thenceinto the throat or throttle bore ofthe carburetor under the action ofvacuum produced by an engine on which the carburetor is mounted. A float18 is positioned in the float chamber for controlling a needle valve 19in a conventional manner to control the supply of fuel F to the floatchamber and to maintain the level of fuel in the float chamber at adesired predetermined level. A vent tube 20 extends upwardly from thefloat chamber 17 and into the air horn ll of the carburetor for ventingthe float chamber in a well-known manner.

A main or primary metering jet 21 is fitted in the carburetor at thebottom of the float chamber 17 for metering the rate at which fuel issupplied from the float chamber to the main discharge nozzle 16, andalso for controlling the rate at which the fuel is supplied to an idletube 22 and thence to an idle passage 23 extending through the crossmember 15 and downwardly through the wall of the carburetor beyond theventuri l4 and into the area of the throttle bore 13.

The lower end of the idle passage 23 terminates at its lower end in atransversely extending bore 24, having a threaded outer end portion 25extended through the outside wall of the carburetor and a reduceddiameter, cylindrical inner portion or idle discharge port 26 openinginto the throttle bore 13 of the carburetor.

A second transverse bore or port 27 extends through the wall of thethrottle bore 13 and into the idle passage 23 in upwardly spacedrelationship to the discharge port 26.

A throttle valve or plate 28 is pivotally mounted in the throttle bore13 in a position such that when in its closed position, as shown inFIGS. 1 and 3, the edge of the throttle plate is disposed adjacent theside wall of the throttle bore between the ports 26 and 27 in the idlecontrol circuit.

An elongate idle adjusting screw 29 is threadably adjustably received inthe threaded portion of bore 24, and includes a first cylindricalportion 30 disposed in the bore 24 in alignment with the idle supplypassage 23, and an elongate, reduced diameter, cylindrical end portion31 extended through the idle discharge port 26 and into the throttlebore of the carburetor. The screw 29 is externally threaded, as at 32,for cooperation with the threaded portion 25 in the carburetor, and acoil spring 33 is disposed around the outer threaded end portion of thescrew 29 for maintaining a predetermined amount of tension on the screwto prevent the screw from accidentally working loose or moving from itsset position once adjusted. The outer end of the screw is enlarged andknurled at 34 so that the screw may be manipulated with fingers and ascrew slot 35 is also provided in the outer end of the screw formanipulation of the screw with a suitable tool, such as a screwdriver orthe like.

An elongate passageway 36 is formed through the center of the screw 29and opens outwardly through the opposite ends of the screw. A radiallyextending passageway or port 37 is formed through the side of screw 29in the midportion 30 thereof, and the radial port or bore 37 has a crosssectional area approximately one-half as great as the cross sectionalarea of idle supply passage 23. The inner end of passage 36 isdiametrically enlarged at 38, and the cross sectional area of portion 38is the same as the cross sectional area of radial bore or port 37,whereas the outer portion 36 of the axial passageway has a crosssectional area approximately one-half as great as the cross sectionalarea of inner portion 38.

The length of the inner end portion 31 of screw 29 is such that with thescrew adjusted to bring the radial port 37 in registry with the idlesupply passage 23, the inner end of portion 31 projects into thethrottle bore in spaced relationship to the side wall thereof. Further,as seen in FIGS. 4 and 5, the idle adjustment screw 29 can be adjustedfor full flow, as in FIG. 4, with the port 37 axially aligned with thesupply passage 23, or for partial or restricted flow, as in FIG. 5, withthe port 37 out of alignment with the passage 23.

Thus with the present invention, when the idle screw 29 is properlyadjusted, and the throttle plate or valve 28 of the carburetor isclosed, air flows inwardly through port 27 and to the supply passage 23and fuel is supplied through passage 23 to the transverse bore 24, andthence into the radial port 37 of screw 29, whereat the air and fuel arefurther intermixed with further air flowing inwardly through the passage36 in the screw 29. The air and fuel are intermixed in the enlargeddiameter portion 38 of the screw and are discharged from the inner endthereof into the throttle bore in substantially spaced relation to thewall of the throttle bore, so that the turbulence within the throttlebore effectively atomizes the fuel and thoroughly intermixes the air andfuel, whereby more complete and ef ficient combustion takes place withthe result that less fuel is consumed and air pollution is reduced.

The idle screw 29 of the present invention may be used with existing,conventional carburetors without requiring modification thereof, anddifferent screws may be provided for use on different types or makes ofcarburetors.

To use the idle screw of the present invention, the existing,conventional idle screw in the carburetor is removed and the idle screwof the invention is threaded into the opening for the idle screw, withthe cylindrical portion 31 of the idle screw slidably extending into andthrough the idle discharge port 26, rather than seating against theinner end of the port as with conventional idle screws. The fit ofportion 31 in the idle discharge port 26 is such as to preclude flow offuel around the portion 31, and the rate of flow of fuel may thus beaccurately regulated by merely orienting radial port 37 relative topassage 23.

As this invention may be embodied in several forms without departingfrom the spirit or essential characteristics thereof, the presentembodiment is, therefore, illustrative and not restrictive, since thescope of the invention is defined by the appended claims rather than bythe description preceding them, and all changes that fall within themetes and bounds of the claims or that form their functional as well asconjointly cooperative equivalents are, therefore, intended to beembraced by those claims.

I claim:

1. In a carburetor having a side wall defining an air horn and athrottle bore in communication with the air horn, a throttle valve inthe throttle bore for controlling flow of air and fuel therethrough,said side wall having a radial bore therethrough spaced below thethrottle valve and including an inner end portion defining an idle fueldischarge port opening into the throttle bore, an idle fuel supplypassage means in communication at one end with a fuel supply and incommunication at the other end with the radial bore, the improvementcomprising an elongage idle mixture control screw extended completelythrough the radial bore in the side wall of the carburetor and having ascrew threaded outer end portion threadably engaged in said radial boreand extending outside the carburetor and having a smooth, cylindricalinner end portion sealingly and slidably engaged in and extended throughthe idle fuel discharge port and into the throttle bore of thecarburetor and precluding flow of fuel through said discharge portaround said screw, said screw having an axial passage therethroughopening through the opposite ends thereof and a radial passagecommunicating at its inner end with the axial passage and at its outerend with the idle fuel supply passage means, so that air is drawn fromatmosphere into the axial passage and fuel is drawn through the radialpassage into the axial passage and is mixed with air therein, saidair-fuel mixture discharged through said inner end of the screw into thethrottle bore of the carburetor spaced from the side wall thereof forthorough mixing and atomization of the fuel and air and thus resultingin more efficient operation and reduced fuel consumption and less airpollutlOl'l.

2. An idle control screw for a carburetor, comprising an elongateexternally threaded cylindrical body adapted to extend through the sideof a carburetor and having an elongate, cylindrical, inner end portionadapted to project through an idle fuel discharge port of the carburetorand into a throttle bore portion of the carburetor, said body having anaxial passage therethrough opening through the opposite ends thereof anda radial passage through the side thereof in communication at its innerend with the axial passage and adapted to be placed in registry at itsouter end with an idle fuel supply passage of the carburetor so that inuse air is drawn in through the axial passage and fuel is drawn inthrough the radial passage, said air and fuel being premixed in theaxial passage and then discharged through the inner end portion into thethrottle bore of the carburetor in spaced relation to the wall of thethrottle bore for thorough mixing and atomization of the fuel and airand thus resulting in more efficient operation and less fuel consumptionand reduced air pollution.

3. The improvement as in claim 1, wherein the axial passage through thescrew has a first diameter at the outer end of the screw and a second,larger diameter at the inner end of the screw, said radial passagecommunicating with said larger diameter, second portion of the axialpassage adjacent the juncture of the first and second portions of theaxial passage, and said radial passage has the same diameter as saidlarger diameter portion.

4. The improvement as in claim 3, wherein the radial passage and saidlarger diameter portion of the axial passage have a cross-sectional areasubstantially twice as great as the cross-sectional area of the firstportion of the axial passage.

5. The improvement as in claim 4, wherein the radial passage and largerdiameter portion of the axial passage have a cross-sectional areasubstantially one-half as great as the cross-sectional area of the idlefuel supply passage in the carburetor.

6. The improvement as in claim 1, wherein the screw is externallythreaded from adjacent the radial passage therein outwardly to saidouter end thereof for cooperation with complemental threads in theradial bore in the carburetor, said screw being adjustable to bring theradial passage therein into more or less aligned registry with thecarburetor idle fuel supply passage to thus regulate the amount of fuelsupplied therethrough.

7. The improvement in claim 6, wherein the cylindrical inner end portionof the screw is of reduced diameter relative to the externally threadedportion thereof. a

1. IN A CARBURETOR HAVING SIDE WALL DEFINING AN AIR HORN AND A THROTTLEBORE IN COMMUNICATION WITH THE AIR HORN, A THROTTLE VALE IN THE THROTTLEBORE FOR CONTROLLING FLOW OF AND AND FUEL THERETHROUGH, SAID SIDE WALLHAVING A RADICAL BORE THERETHROUGH SPACED BELOW THE THROTTLE VALVEINCLUDING AN INNER END PORTION DEFINING AN IDLE FUEL DISCHARGE PORTOPENING NTO THE THROTTLE BORE, AND IDLE FUEL SUPPLY PASSAGE MEANS INCOMMUNICATION AT ONE END WITH A FUEL SUPPLY AND IN COMMUNICATION AT THEOTHER END WITH THE RADIAL BORE, THE IMPROVEMENT COMPRISING AN ELONGAGEIDLE MIXTURE CONTROL SCREW EXTENDED COMPLETLY THROUGH THE RADIAL BORE INTHE SIDE WALL OF THE CARBURETOR AND HAVING A SCREW THREADED OUTER ENDPOTION THREADABLY ENGAGED IN SAID RADIAL BORE AND EXTENDING OUTSIDE THECARBURETOR AND HAVING A SMOOTH, CYLINDRICAL INNER END PORTION SEALINGLYAND SLIDABLY ENGAGED IN AND EXTENDED THROUGH THE IDLE FUEL DISCHARGEPORT AND INTO THE THROTTLE BORE OF THE CARBURETOR AND PRECLUDING FLOW OFFUEL THROUGH SAID DISCHARGE PORT AROUND SAID SCREW, SAID SCREW HAVING ANAXIAL PASSAGE THERETHROUGH OPENING THROUGH THE OPPOSITE ENDS THEREOF ANDA RADIAL PASSAGE COMMUNICATING AT ITS INNER END WITH THE AXIAL PASSAGEAND AT ITS OUTER END WITH THE IDLE FUEL SUPPLY PASSAGE MEANS SO THAT AIRIS DRAWN FROM THE ATMOSPHERE INTO THE AXIAL PASSAGE AND FUEL IS DRAWNTHROUGH THE RADIAL PASSAGE INTO THE AXIAL PASSAGE AND IS MIXED WITH AIRTHEREIN, SAID AIR-FUEL MIXTURE DISCHARGED THROUGH SAID INNER END OF THESCREW INTO THE THROTTLE BORE OF THE CARBURETOR SPACED FROM THE SIDE WALLTHEREOF FOR THROUGH MIXING AND ATOMIZATION OF THE FUEL AND AIR AND THUSRESULTING IN MORE EFFICIENT OPERATION AND REDUCED FUEL COMSUMPTION ANDLESS AIR POLLUTION.
 2. An idle control screw for a carburetor,comprising an elongate externally threaded cylindrical body adapted toextend through the side of a carburetor and having an elongate,cylindrical, inner end portion adapted to project through an idle fueldischarge port of the carburetor and into a throttle bore portion of thecarburetor, said body having an axial passage therethrough openingthrough the opposite ends thereof and a radial passage through the sidethereof in communication at its inner end with the axial passage andadapted to be placed in registry at its outer end with an idle fuelsupply passage of the carburetor, so that in use air is drawn in throughthe axial passage and fuel is drawn in through the radial passage, saidair and fuel being premixed in the axial passage and then dischargedthrough the inner end portion into the throttle bore of the carburetorin spaced relation to the wall of the throttle bore for thorough mixingand atomization of the fuel and air and thus resulting in more efficientoperation and less fuel consumption and reduced air pollution.
 3. Theimprovement as in claim 1, wherein the axiaL passage through the screwhas a first diameter at the outer end of the screw and a second, largerdiameter at the inner end of the screw, said radial passagecommunicating with said larger diameter, second portion of the axialpassage adjacent the juncture of the first and second portions of theaxial passage, and said radial passage has the same diameter as saidlarger diameter portion.
 4. The improvement as in claim 3, wherein theradial passage and said larger diameter portion of the axial passagehave a cross-sectional area substantially twice as great as thecross-sectional area of the first portion of the axial passage.
 5. Theimprovement as in claim 4, wherein the radial passage and largerdiameter portion of the axial passage have a cross-sectional areasubstantially one-half as great as the cross-sectional area of the idlefuel supply passage in the carburetor.
 6. The improvement as in claim 1,wherein the screw is externally threaded from adjacent the radialpassage therein outwardly to said outer end thereof for cooperation withcomplemental threads in the radial bore in the carburetor, said screwbeing adjustable to bring the radial passage therein into more or lessaligned registry with the carburetor idle fuel supply passage to thusregulate the amount of fuel supplied therethrough.
 7. The improvement inclaim 6, wherein the cylindrical inner end portion of the screw is ofreduced diameter relative to the externally threaded portion thereof.